跨努森数区域的微通道内流动计算模拟研究

Investigations of micro-channel flows in different flow regimes

中文关键词: 微通道  努森数  雷诺数  滑移模型

英文关键词: micro-channel  the Knudsen number  the Reynolds number  slip model

中文摘要:

      采用一阶和修正二阶的滑移连续介质模型,对跨努森数区域的低速微通道流进行二维和三维数值模拟。用实验结果和DSMC方法验证滑移连续介质模型在跨努森数区域中的适用性,并详细讨论了微通道流的可压缩效应、稀薄效应、低雷诺数效应和三维特性。研究表明,努森数是表征稀薄效应和模型适用性的特征参数,滑移连续介质模型适用于努森数小于0.150的氮气流动；马赫数不再是微通道流可压缩效应的唯一标识参数；雷诺数是表征低雷诺数效应和三维特性的关键参数,高宽比大于20的微通道流具备良好的二维特性。

英文摘要:

      The two-dimensional and three-dimensional modeling are performed to investigate the low Mach number gaseous flows in micro-channels using the first order and the alternative second order continuum-based slip models, respectively. The validity of slip models is examined by the corresponding experiments and the DSMC method under different Knudsen numbers. Moreover, the compressibility effects, rarefaction effects, low Reynolds number effects and three-dimensional characteristics of micro-channel flows are discussed in detail. Simulations have shown that the Knudsen number is a key parameter to determine the magnitude of rarefaction effects and the validity of slip models. The present continuum-based slip models have been also demonstrated to be appropriate for micro-channel nitrogen flows with Kn<0.15. The Mach number is not the unique parameter to govern the compressibility effects of micro-channel flows. The Reynolds number is the key parameter to represent the low Reynolds number effects and three-dimensional characteristics. The results have shown that the micro-channel flows with the height to width ratio in excess of 20, have a good 2D characteristic.